In recent years, in addition to an increasing speed and increasing information volume in information communications such as the Internet, optical networking for two-way communications and large-volume communications is recently developing. Data communication service using optical fibers is being introduced also in general homes, i.e., FTTH (Fiber To The Home). Thus, in addition to information communications through telephone lines using conventional conductive wires, information communications using optical fiber cables are also increasing.
Conventionally, electric power lines, telephone lines, TV signal lines and the like are coupled to various kinds of electronic devices via an outlet device attached to a wall surface. When an optical fiber cable is introduced as a new communication means, there is a need for an easy connection to an information equipment also using such an outlet device. However, in a case of optical fiber cables, there are limitations to a bend radius, etc. since they use of glass fibers, and they require an reinforcement at a coupling part between the optical fibers. Accordingly, there is a large difference in its configuration when compared with the conventional outlet devices which make connections using conductive wires.
For example, JP2004-157263A discloses an outlet device for coupling an optical fiber cable. FIG. 5 shows an outlet device 1 disclosed in JP2004-157263A. The outlet device 1 has an optical fiber receiving plate 2 and a cover plate 3 which are formed of synthetic resin or the like. A plate surface 6 on a front side of the cover plate 3 is formed with a connection port for electric connection. For example, the connection port is configured such that a telephone jack 4 is attached to be exposed from a receptacle hole 5. A telephone plug 7 is coupled to the connection port from the front of the plate surface 6. An optical connector coupling adaptor 8 is attached to a lower portion of the outlet device 1 such that an optical connection port of the optical connector coupling adaptor 8 is oriented downward. An optical connector plug 9 is inserted and coupled to the connection port of the optical connector coupling adaptor 8 from below and in a direction parallel to the plate surface 6.
FIG. 6 shows an example of a configuration of the optical fiber receiving plate 2. The optical fiber receiving plate 2 is attached to a face of an outlet box or the like with a fixing screw 10. A single-fiber or multi-fiber cable led out from the inside of the wall is fixed to the optical fiber receiving plate 2, and a coated optical fiber 11 exposed from the optical fiber cable is accommodated in the optical fiber receiving plate 2. The optical fiber receiving plate 2 is formed by integrally molding a bottom wall 13 and a side wall 12. Circular annular walls 13a, 13b are provided integrally with a central portion of the bottom wall 13. The annular walls 13a, 13b guide the coated optical fiber 11 such that the coated optical fiber 11 is accommodated in a looped manner.
A plurality of optical fiber holding pieces 14a, 14b are provided at suitable intervals integrally with the side wall 12 and the annular walls 13a, 13b. A receptacle hole 15 for the telephone jack 4 is formed on an inner side the annular wall 13a. Cutout holes 16a, 16b through which the optical fiber cable is led out from the inside of the wall toward the front side of the optical fiber receiving plate 2 are formed in the central portion of the bottom wall 13. Optical fiber fixing pieces 17a, 17b are provided integrally with the bottom wall 13 so as to protrude into the cutout holes 16a, 16b respectively. The optical fiber cable is anchored to one of the optical fiber fixing pieces 17a, 17b. A surplus length of the coated optical fiber 11 exposed from the optical fiber cable is accommodated in a looped manner inside the optical fiber receiving plate 2. An optical connector 18 is attached to an end portion of the coated optical fiber 11, and the optical connector 18 is fitted to the optical connector coupling adaptor 8.
As described above, the optical fiber cable, such as a drop optical cable or an indoor optical cable, led indoors is held by the optical fiber fixing piece 17a, 17b. After that, the coated optical fiber 11 is exposed from the optical fiber cable so as to ensure a certain surplus length. The optical connector 18 is attached to the end portion of the coated optical fiber 11, and an optical connection port to the outside is provided via the optical connector coupling adaptor 8. It is therefore necessary to ensure a space for accommodating the surplus length of the coated optical fiber 11 and a coupling portion of the coated optical fiber 11 by using the optical fiber receiving plate 2. It is also necessary to remove a cable sheath to expose the coated optical fiber 11 and to perform an optical fiber connection work.
On the other hand, in recent years, a technique for attaching an optical connector directly to an optical fiber cable for indoor interconnection is also being developed. In a case in which this optical connector is used for the optical interconnection in the outlet device 1 described above, the optical connector can be attached directly to an optical fiber cable led into the optical fiber receiving plate. Accordingly, it becomes unnecessary to perform a connection work between coated optical fibers, becomes possible to accommodate the surplus length of the coated optical fiber in another place, for example, in the inside of the wall. That is, a space inside the outlet device for accommodating an optical fiber can be reduced to a required minimum, and a workload for optical interconnection can be relieved.
However, a drop optical cable or an indoor optical cable to be laid indoors usually has tension members arranged on respective sides of its coated optical fiber, and a section of a cable sheath is rectangular. Therefore, the optical cable is rigid and has directionality in its bending direction. Further, the optical connection port to an external optical fiber cable is required to be configured in a downwardly oriented manner. Thus, a composite outlet device having an electric connection port for electric power, telephone, etc. becomes large in profile that is protrudes from the wall surface. Consequently, there has been a problem that it is likely to be externally damaged and looks poor in appearance.